Glass testing for geeks

 Caution: glass geek post!. One problem that frequently arises is how to get rid of surface devitrification (ugly scum that shows up on fired glass). Some things that cause it: residue from my glass cleaner or drying rags, dust from my adjacent clay studio, glue that gets used to hold glass in place while carefully transporting it to the kiln, finger prints, price tag goo, etc. 

In the glass community groups devitrification (aka devit) is a frequent topic of discussion. People ask for advice on how to clean their glass before firing, and which glass glue works best. All sorts of answers pop up, with not a lot of side by side tests. As a software engineer learning fused glass, it helps me learn if I test. I tested 20 different scenarios with 3 different COE 96 clear glass types that I had in stock: Oceanside Crystal clear, Oceanside icicle clear, and Wissmach clear. Each test consisted of a 1x1 inch square of glass with a cleaning method, and possibly a glue substance and glue application. For glue I tested : 100% aloe vera, Elmer’s white glue, a random crafting glue stick, cheap Suave hairspray. I also tested my 100% mineral oil cutting oil, a fingerprint, price tag goo left on,  and my black sharpie to see how well they burn off. And I left one control square: no cleaning of any way shape or form. I fired them all to a full fuse at 1480 with 20 minute hold.

Here’s what I learned: 

1. Wissmach consistently left a faint outline of each glass square, Oceanside did not. Wissmach also just wasn’t as “clear” when holding the sheet up to the light.
2. My 100% aloe vera doesn’t burn out cleanly. Dang, was hoping it would.
3. Glue stick and white Elmer’s did not burn out
4. El Cheapo hairspray worked. Cutting oil was clean, sharpie burned out completely.
5. Vinegar and distilled water clean the best. 90% alcohol left a haze in cleaning.

Trying to show photos of every devit test is just nuts, because glass is so hard to photograph, but I will share one photo before fuse, and one after fuse off my testing. I marked the upper left corner of each as a registration mark.